On the gene Pn responsible for the development of anthocyanin coloration in stem node of rice.

Abstract

The anthocyanin coloration in the stem node of rice is d, eveloped by the action of the complementary effeof of the three genes C, Sp and pn, that is : C : the gene responsible for the formation of chromogenic substance ; 'Sp : the gene which converts the chromogenic substance to anthocyanin ; Pn : the gene responsible for spreading the anthocyanin pigments to the sterp node. The co-existence of the genes C and. Sp gives anthocyanin coloration at the apiculus as well as empty glumes in the spikelet. Each af, these genes comprises respectively of the following multiple alleles, the dorpinance runing in the given order, namely : CB > CBp > Cn >, c and Sp > Spd > sp The expression of anthocyanin color characters of apiculus is determined .according to the mode of combinations between the above trienti ?? ned ge-nes. Thtis the stem node color is found in plants which have spikelets with some arithocyanin co-loration, no plants with green zipiculus but colored, stem node being able to find. Put it into other words the Pn is effective only when it acts toge-ther with both genes of C arie Sp. In the crossing ekperiments of ours, the gehe Pn was found to be linked to the gene Sp, the recombination value being counted roughly to be 18 per cent. Saying as to the segregation of 1055 F2 plan, ts, the total of the three crosses, 721 had purple apiculus and colored node (C Sp Pn):, 89 had purD. Ie apiculus and green node (C Sp pn), 82 had red apiculus and colored node (C Spd 'pn) and 163 had red apiculus and green nod (C Spd pn). These ntimbere aree well with the calcula-ted ratio of 323 : 40 : 40:81 which is based on the gametic ratio of 4. 5 : I : I : 4.5, showing the existence of linkage relation between the genes Pn and Sp.