Primary Study In Vitro Culture Of Summer Squash

Summer squash(Cucurbia pepo L.)is one of gourd vegetables,and its protected cultivation area is next only to cucumbers’ now.Summer squash displays a strong heterosis,but the conventional breeding is going to restrict the breeding speed of F1 hybrids to a certain degree.Therefore,it is significant to find a quick method to get F1 hybrids.Using anther culture can shorten the breeding period to get haploid plant and it also accelerates the breeding progress.In this study,it uses ‘Zhenyu 10’ summer squash as experimental material to start a research on anther culture.It explores the relationship between microspores and buds of summer squash in developmental stages.At first,the experiment find out the proper medium formula for anther callus induction,and then it studies the redifferentiation from the callus.Besides,it also researches on the POD activity and soluble protein content in Summer squash anther callus.The main results are as follow:1.The average lengths of vertical and horizontal diameter of the flower buds in the tetrad stage are 0.98±0.03 cm and 0.47±0.04 cm.The average lengths of vertical and horizontal diameter of the flower buds in the early-uninucleate stage are 1.07±0.03 cm and 0.50±0.02 cm.The average lengths of vertical and horizontal diameter of the flower buds in the late-uninucleate stage are 1.17±0.03 cm and 0.55±0.03 cm.The average lengths of vertical and horizontal diameter of the flower buds in the binucleate stage are 1.27±0.03 cm and 0.61±0.03 cm.There are significant differences on the average lengths of vertical and horizontal diameter of the flower buds in different stages.As for the male flowers on the first nine nodes of ‘Zhen Yu 10’,the maximum difference between the average lengths of vertical and horizontal diameter of the flower buds in the same stage is 0.03 cm,but the difference was not obvious between different nodes.2.The low-temperature(4℃)treatment has some effects on the induction rate of summer squash anther callus and the survival rate of pollen.After 2 ~ 3 days low-temperature treatment,the maximums of the induction rate of the anther callus are 70.42% and 69.87%,and the survival rates of pollen are 69.86% and 61.16%.After 4-day low-temperature treatment,both of the two rates above decrease significantly.Therefore,the best low-temperature processing time is 2-3 days,and it should not be too long.3.The induction rate of summer squash anther callus decreases with the increase of sucrose concentration,while the callus formation time increases.Higher concentrations of sucrose can effectively suppress induction callus of somatic cell.Therefore,it is appropriate to add 50g/L sucrose into the growth medium.4.Culture conditions have an important influence on callus inductions.After one-week dark incubation,the highest callus induction rate is 50.71%,and the color of calluses is yellow-green.5.In the MS medium,when concentration of NAA is 2.0mg / L,and the concentration of 6-BA is 2.0 mg/L,the highest callus induction rate is 86.41%.6.During the differentiation process of calluses,the POD activity and soluble protein content show some regular changes.The value of POD activity fluctuates strongly,but soluble protein content increases and then shows a downward trend.