Exploitation and Genetic Identification of Triploid Plants from Seedling Populations of Orah Mandarin(Citrus reticulata)
Discovering natural triploids from diploid seedling offspring is an effective mehod to cultivate new seedless citrus cultivar.In this study,the small plump seeds of Orah were germinated and sowed,and the ploidy of seedling offsprings was identified by morphological screening,flow cytometry and chromosome counting.A total of 98 triploid lines of Orah seedlings were obtained.Two pairs of SSR primers with polymorphism between the female parent and its candidate male parent were used to analyze the hybrid origin of triploid progenies.It was found that only the amplification product of Orah mandarin could be detected in the triploid progenies.Further genetic analysis was performed using 36 pairs of S-RNase primers.Results showed that the S genotype S11/SMof Orah mandarin was detected in all triploid progenies,and the S genotype S22 of the candidate male parent Shatangju occurred in two lines,presumed that these two lines were triploid progenies produced by the hybridization of Orah and Shatangju,and were formed by fertilization of 2n female gametes.The remaining lines might be autotriploids produced by selfing of Orah.Compared with the diploid seedlings,the triploid seedlings of the same age grew slowly,the internodes became shorter,the dwarfing was obvious,the main roots were short and thick,the fibrous roots were less,the leaves were dark green and thicker.Under the same cultivation and management conditions,the expression of multiple stress response related genes(CitCOMT,CitGRAS,CitERF4 and CitERF9)in the leaves of allotriploid plants was significantly up-regulated compared with diploid and autotriploid plants.
万方数据
维普
