Geographical variation of needles phenotypic and anatomic traits between populations of Pinus yunnanensis var. tenuifolia and its environmental interpretation

doi:10.17521/cjpe.2023.0041

Abstract

Abstract:

Aims Leaf is an important organ for forest trees to acquire and utilize survival resources, and its morphological structure reflects the habitat adaptability of trees to a certain extent. Exploring the role of geography and climate of the Nanpan-Hongshui River basin in shaping the needles morphology and microstructure of an important tree species in the region, Pinus yunnanensis var. tenuifolia, has important reference value for understanding the ecological adaptability and resource conservation of this tree species.

Methods Eighteen morphological and microscopic characters of nine wild populations which distributed in Guizhou and Guangxi were measured, and seven geographical and climatic factors of the nine population locations were recorded. The population divergence and environmental associations were analyzed by nested ANOVA, correlation analysis, multivariate statistical analysis (principal component analysis, redundancy analysis, and hierarchical clustering analysis).

Important findings The results showed that, except for the ratio of needle cross-sectional area to central cylinder area (V1), all indicators had different degrees of differentiation among populations (phenotypic differentiation coefficient (V_ST) = 22.32%-51.42%). It implied that the habitat heterogeneity among populations had a significant impact on most indicators. Pearson correlation analysis and multivariate statistical analysis showed that the indicators which related to needle resin canals (resin canals number, resin canals perimeter, resin canals area, etc.) increased with the increase of latitude, altitude, and mean annual precipitation, but decreased with the increase of mean annual temperature; the stomatal indicators (stomatal density, ratio of stomatal density to V1) increased with increasing latitude and longitude, and decreased with increasing relative humidity; the indicators which related to the needle cross-sectional size (needle width, needle thickness, needle cross-sectional area, central cylinder area, etc.) are mainly affected by the distance from the sampling site to the Nanpan-Hongshui River. The closer the distance, the smaller the indicator value is. To sum up, P. yunnanensis var. tenuifolia exhibits a trend of miniaturization of resin canal, which was driven by dry-hot habitat selection that is different from that of the original species Pinus yunnanensis. Its higher stomatal density (and sunken stomata) is conducive to balancing respiration and transpiration dehydration in arid environments. The relatively slender needles may be mainly shaped by the stress effects of foehn and strong canyon winds which caused by the special valley terrain in the region, as well as the growth limiting effects of seasonal warm and dry climate on needles.

Key words: ecological adaptivity, dry-hot habitat, geographical factor, climatic factor, geographical variation, resource conservation

FENG Shan-Shan, HUANG Chun-Hui, TANG Meng-Yun, JIANG Wei-Xin, BAI Tian-Dao. Geographical variation of needles phenotypic and anatomic traits between populations of Pinus yunnanensis var. tenuifolia and its environmental interpretation[J]. Chin J Plant Ecol, 2023, 47(8): 1116-1130.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2023.0041

https://www.plant-ecology.com/EN/Y2023/V47/I8/1116

Figures/Tables 10

Fig. 1 Sampling sites of Pinus yunnanensis var. tenuifolia.

Table 1 Names, abbreviations, and units of tested needle characters for Pinus yunnanensis var. tenuifolia

性状缩写 Abbreviation of character	单位 Unit	性状名称 Name of character
α_A	°	针叶截面夹角 Angle of needle cross section
NW	mm	叶宽 Needle width
NT	mm	叶厚 Needle thickness
NSP	mm	叶截面周长 Needle cross-section perimeter
NSA	mm²	叶截面面积 Needle cross-section area
CCW	mm	中柱宽 Central cylinder width
CCT	mm	中柱厚 Central cylinder thickness
CCP	mm	中柱截面周长 Central cylinder perimeter
CCA	mm2	中柱截面面积 Central cylinder area
RCN	No.	树脂道数 Number of resin canals
RCP	mm	树脂道总周长 Resin canal perimeter
RCA	mm2	树脂道总面积 Resin canal area
MA	mm2	叶肉面积 Mesophyll area
MSD	No.·mm^-2	气孔密度 Mean stomatal density
V1		叶截面面积与中柱截面面积之比 NSA/CCA
V2		树脂道数与气孔密度之比 RCN/MSD
V3		树脂道数与V1之比 RCN/V1
V4		气孔密度与V1之比 MSD/V1

Fig. 2 Needle microscopic structures of Pinus yunnanensis var. tenuifolia. A, Stomata and stomatal line distribution. B, Cross section of needle. C, Enlarged exodermis, resin canal and stomata. D, Model picture of cross section of needle. αA, angle of needle cross section; c, central cylinder; e, epidermis; h, subcutaneous layer; m, mesophyll; p, phloem; r, resin canal; s, stomata; x, xylem. CCT, central cylinder thickness; CCW, central cylinder width; NT, needle thickness; NW, needle width; RCA, resin canal area; RCP, resin canal perimeter.

Table 2 F value, percentage of variance component among and within populations of needle characters and phenotypic differentiation coefficient of Pinus yunnanensis var. tenuifolia

性状 Trait	F		方差分量百分比 Percentage of variance component (%)			表型分化系数 Phenotypic differentiation coefficient (V_ST, %)
性状 Trait	种群间 Among populations	种群内 Within population	种群间 Among populations	种群内 Within population	随机误差 Random error	表型分化系数 Phenotypic differentiation coefficient (V_ST, %)
α_A	2.49 ^*	1.59^*	2.83	9.85	87.32	22.32
NW	16.88^***	3.52^***	17.99	27.13	54.88	39.87
NT	14.83^***	2.92^***	17.64	22.57	59.79	43.86
NSP	12.40^***	3.41^***	13.59	27.62	58.79	32.98
NSA	13.74^***	3.20^***	15.54	25.43	59.04	37.93
CCW	11.04^***	2.38^***	14.36	18.21	67.43	44.09
CCT	3.68^***	1.46^*	5.68	7.74	86.58	42.31
CCP	7.62^***	2.36^***	10.27	18.87	70.86	35.24
CCA	6.96^***	2.17^***	9.37	16.71	73.92	35.94
RCN	55.63^***	11.90^***	26.79	50.01	23.20	34.88
RCP	39.13^***	9.31^***	22.44	49.66	27.90	31.13
RCA	20.74^***	7.02^***	15.23	45.99	38.77	24.88
MA	17.64^***	4.80^***	15.95	35.87	48.18	30.78
MSD	12.04^***	2.33^***	18.08	17.08	64.85	51.42
V1	1.70	3.90^***	0.00	34.08	65.92	0.00
V2	22.60^***	5.68^***	18.68	38.97	42.35	32.40
V3	44.45^***	10.77^***	23.25	50.53	26.22	31.51
V4	10.02^***	2.95^***	12.78	24.17	63.04	34.59
平均值 Mean			14.47	28.92	56.61	33.67

Table 3 Tukey HSD test on the needle traits between populations of Pinus yunnanensis var. tenuifolia (mean ± SD)

Fig. 3 Pearson correlations between needle characters of Pinus yunnanensis var. tenuifolia and geographical and climatic factors. ***, p < 0.001; **, p < 0.01; *, p < 0.05. αA, angle of needle cross section; CCA, central cylinder area; CCP, central cylinder perimeter; CCT, central cylinder thickness; CCW, central cylinder width; MA, mesophyll area; MSD, mean stomatal density; NSP, needle cross-section perimeter; NSA, needle cross-section area; NT, needle thickness; NW, needle width; RCA, resin canal area; RCN, number of resin canals; RCP, resin canal perimeter; V1, NSA/CCA; V2, RCN/MSD; V3, RCN/V1; V4, MSD/V1. ALT, altitude; DFSSR, distance from sampling site to river; LAT, latitude; LON, longitude; MAP, annual precipitation; MAT, mean annual air temperature; MRH, mean relative humidity.

Table 4 Principal component (PC) analysis of geographical and climatic factors for needle characters of Pinus yunnanensis var. tenuifolia populations

地理和气候因子 Geographical and climatic factor	主成分载荷 Principal component loading
地理和气候因子 Geographical and climatic factor	PC1	PC2	PC3	PC4
纬度 Latitude	0.213	-0.877	0.380	0.152
经度 Longitude	-0.850	-0.360	0.369	-0.010
年平均气温 Mean annual air temperature	-0.869	0.441	-0.100	0.044
相对湿度 Mean relative humidity	0.205	0.902	0.242	-0.238
年降水量 Mean annual precipitation	0.867	0.306	-0.259	0.274
海拔 Altitude	0.838	-0.288	0.321	-0.252
采样点至河流距离 Distance from sampling site to river	0.079	0.704	0.660	0.241
特征值 Eigenvalue	3.02	2.58	0.95	0.28
贡献率 Contribution rate (%)	43.21	36.85	13.64	3.98

Fig. 4 Regression analysis between principal components (PC) of geographical and climatic factors and needle characters of Pinus yunnanensis var. tenuifolia populations (mean ± SE). A-E are characters that have significant regression with PC1. F-G are characters that have significant regression with PC2. MSD, mean stomatal density; RCA, resin canal area; RCN, number of resin canals; RCP, resin canal perimeter; V1, needle cross-section area divided by central cylinder area (NSA/CCA); V2, RCN/MSD; V3, RCN/V1; V4, MSD/V1.

Fig. 5 Redundancy analysis (RDA) between needle characters and geo-climatic factors of Pinus yunnanensis var. tenuifolia populations. αA, angle of needle cross section; CCA, central cylinder area; CCP, central cylinder perimeter; CCT, central cylinder thickness; CCW, central cylinder width; MA, mesophyll area; MSD, mean stomatal density; NSA, needle cross-section area; NSP, needle cross-section perimeter; NT, needle thickness; NW, needle width; RCA, resin canal area; RCN, number of resin canals; RCP, resin canal perimeter; V1, NSA/CCA; V2, RCN/MSD; V3, RCN/V1; V4, MSD/V1.

Fig. 6 Optimal number of clusters (A-C) and hierarchical cluster tree (D) of geographical and climatic factors and needle traits of Pinus yunnanensis var. tenuifolia populations. A, Optimal number of clusters of populations based on needle traits. B, Optimal number of clusters of geographical and climatic factors. C, Optimal number of clusters of needle traits. D, Cluster results of needle traits and geographical and climatic factors in the tested populations. αA, angle of needle cross section; CCA, central cylinder area; CCP, central cylinder perimeter; CCT, central cylinder thickness; CCW, central cylinder width; MA, mesophyll area; MSD, mean stomatal density; NSA, needle cross-section area; NT, needle thickness; NW, needle width; NSP, needle cross-section perimeter; RCA, resin canal area; RCN, number of resin canals; RCP, resin canal perimeter; V1, NSA/CCA; V2, RCN/MSD; V3, RCN/V1; V4, MSD/V1. ALT, altitude; DFSSR, distance from sampling site to river; LAT, latitude; LON, longitude; MAP, annual precipitation; MAT, mean annual air temperature; MRH, mean relative humidity. The values of needle character and geographical and climatic factors in plot D were standardized before visualization.

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