|Authors: ||S. Goto, T. Yoshioka, M. Kita, S. Ohta, T. Shimizu|
|Keywords: ||citrus, seedlessness, breeding, pollen number, lactophenol blue|
Seedlessness is an important trait in citrus breeding.
Male sterility derived from Satsuma has been used in Japanese citrus breeding programs to obtain seedless cultivars.
Evaluation of male sterility has focused on the degree of anther development; however, its inheritance when derived from Satsuma has not been fully determined.
In this study, we evaluated male sterility to clarify its inheritance by using three cross populations that were derived from promising offspring selected from Satsuma parentage.
Initially, we compared three staining dyes for evaluation of male sterility according to the number of grains and apparent fertility of pollen.
The results confirmed that lactophenol blue is effective for this purpose.
We applied lactophenol blue to verify male sterility in several cultivars.
We established methods to evaluate male sterility by determining the number of pollen grains per anther and their apparent fertility.
Male sterility in three populations (Hyuganatsu × LSQUOOkistu No. 56RSQUO, LSQUOOkitsu No. 46RSQUO × LSQUOOkitsu No. 56RSQUO and LSQUOOkitsu No. 46RSQUO × LSQUOKaraRSQUO) showed obvious changes in the distribution of pollen number per anther.
However, the apparent fertility of pollen was almost constant at approximately 80% in most of the individuals, suggesting no segregation for this trait.
Results show that the number of pollen grains per anther primarily determines male sterility of Satsuma, and this trait is partly inherited by the progenies of LSQUOOkitsu No. 46RSQUO and LSQUOOkitsu No. 56RSQUO. Developing DNA markers closely linked to male sterility is highly anticipated to facilitate seedless breeding.
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