阿月浑子与黄连木远缘杂交不亲和原因分析

A Preliminary Study on Intergeneric Cross-Incompatibility Between Pistacia vera L. and Pistacia chinensis Bunge

【目的】探明阿月浑子与黄连木远缘杂交是否存在授粉障碍。【方法】以阿月浑子和黄连木杂交组合为材料,以阿月浑子自交组合为对照,利用扫描电镜技术观察父本花粉的形态特征,采用离体萌发试验对父本花粉萌发率和活力进行测定,采用压片法对不同授粉组合的花粉管生长动态进行荧光显微观察。【结果】阿月浑子T-491花粉极面观可见4个萌发孔,外壁具稀疏刺状颗粒;黄连木花粉极面观萌发孔仅见2个,外壁有较密刺状颗粒分布;黄连木花粉极轴长和赤轴长分别为53.84μm和44.85μm,均大于阿月浑子T-491雄株花粉。用于授粉的父本黄连木和阿月浑子T-491的花粉萌发率分别为77.3%和84.38%,花粉活力分别为82.4%和89.14%。杂交组合黄连木花粉授粉4 h后开始少量萌发,授粉12 h后花粉管进入花柱,授粉48 h后花粉管进入子房,授粉72 h后到达胚囊。自交组合阿月浑子T-491花粉授粉2 h后即开始大量萌发,6 h后花粉管进入花柱,12 h后花粉管到达花柱基部,24 h后花粉管进入子房;与自交组合相比,杂交组合的黄连木花粉萌发和花粉管生长速度相对滞后,并伴有花粉管弯曲、膨大变粗、花柱中有大量不规则胼胝质沉积等现象。阿月浑子T-491授粉的自交组合坐果率为57%,而黄连木授粉的杂交组合坐果率为26%,杂交组合表现出较低的结实性。【结论】阿月浑子和黄连木远缘杂交的授粉过程存在一定障碍,可能是导致杂交坐果率低的原因之一。

[Objective] The objective of this experiment is to investigate the fertilization barriers of the intergeneric cross between P. vera and P. chinensis. The pollen morphology, the pollen viability and the progress of cross-pollination and fertilization were observed and the intergeneric cross compatibility between P. vera and P. chinensis was studied. [Method] The pollen morphology of male parents was observed by scanning electron microscopy. The pollen germination and the viability were tested by means of in vitro cultivation and the progress of pollen tube growth was observed by fluorescence microscopy. [Result] There are two and four apertures in pollen surface ofP. vera and P. chinensis, respectively, and more dense thorn-like particle in P. chinensis pollen grain than in P vera. The length of polar axis and equatorial axis ofP. chinensis pollen grain were 53.84 ~ri and 44.85 ~n, respectively, which is slightly longer than P. vera pollen grain. The pollen germination rate ofP. chinensis Bunge and T-491 were 77.30% and 84.38% respectively, and the pollen viability ofR chinensis Bunge and T-491 were 82.4% and 89.14%, resoectivelv. The pollen of P chinensis begin to germinate at 4 h, the pollen tubes reached ovary at 48 h and enter embryo sac at 72 h in interspecific-cross after pollination, while the pollen ofP vera T-491 begin to germinate at 2 h, the pollen tubes reached the base of stigma at 12 h and reach to ovary at 24 h. The incompatibility characters such as the pollen tubes bending, swollen and lots of irregular callose depositing in stigma and style were observed in interspecific cross. The percentage of final fruit set was 57% in the self-pollination, while the value was 26% in interspecific-cross which is lower than the former. [Conclusion] A few pollen tubes of P chinensis could enter the style of P vera and reached to the ovary. There were some pollen tube elongation growth barriers at interspecific-cross between P vera and P. chinensis. Abnormal pollen tube growth after pollination may be one of the reasons led to low fruiting rate in intergeneric cross between P vera and P chinensis.