Research of improvement in profitability of tomato cultivation by breeding of disease resistance tomatoes
The purpose of this study is to investigate the effect of world tomato market tendency and cultivation problems on agricultural management. It is obvious that profit has been improved depending on breeding of different disease-resistance variety. Therefore, establishing a continue tomato cultivation business model can be feasible. In chapter 2, in order to prepare a mark of disease-resistance, at first, practical situation of disease occurrence and how to solve the loss by disease for local tomato growers has been investigated. The object is tomato growers in all the country.「The fact finding survey on the effects of diseases in tomato cultivation for farming」was carried out. 50 questionnaire surveys were obtained. The result showed several disease had occurred in tomato producers, among which grey mold disease was most and happened 100% in the past 10 years. Because of occurrence of grey mold disease 372,538 yen was lost in each 10a with chemical cost 105,000 yen and the average of chemical spray were 18.7 times, 30 hours of operation time was needed every year. Second, a survey implied that disease-resistance of tomato feature was optioned better than former variety with a second importance ranking of new tomato feature for growers. It also shows that conscious of disease measures for tomato growers had been improved. So far, throughout related studies the real grey mold disease-resistance genetic gene and a field resistance gene have not been found yet. To observe a mainly field resistance measure, an experiment of exploring host plant susceptibility genes when pathogenic bacteria was inflected. Also the possibility of disease-resistance breeding added on plant by restraining host plant susceptibility genes was discussed. In chapter 3, host plant susceptibility genes, which facilitate pathogen growth during plant infection, are attractive targets for disease-resistance breeding. To explore candidate susceptibility genes in tomatoes during Botrytis cinerea infection, the fungal infection-responsive SWEET genes were screened for out of all 31 tomato SlSWEET genes. The expression of only one gene, SlSWEET15, was induced by B. cinerea at the pre-necrotic stage (16 h post inoculation), whereas most of the other SWEET genes were downregulated. The expression of the SlSWEET15 transiently increased by 16 h post inoculation, then reduced to basal levels by 24 h post inoculation. We measured the glucose and sucrose contents of apoplasmic fluid of infected cotyledons at the pre-necrotic stage (20 h post inoculation). The sugar contents of the apoplasmic fluids were significantly higher in the infected cotyledons compared to 0 h. Furthermore, glucose and sucrose can promote growth and invasion of B. cinerea both in vitro and in vivo. SWEET proteins in clade III, including the deduced SlSWEET15, are well-known sugar efflux transporters. These results suggest that SlSWEET15 is induced by B. cinerea and that this is exploited by the fungus, which may provide sugars to promote hyphal growth in the pre-necrotic stage of infection in tomato. In chapter 4, an analysis of tomato management income and expense for growers was made. Then a simulation on the effect of tomato cultivation profitability applying a new variety with grey mold disease resistance by building a model of grey mold disease was performed. Nowadays there are 3 main cropping types for tomato growers with management income and expense in Japan. The result of cropping type analysis implied that annually minimum of agriculture profit for one person of each generation was 98,000 yen and maximum was 1,448,000 yen. It was difficult to make a living by profit of tomato production in average cultivation area. To solve the living problem, at first it was proposed that agriculture rough profit should be improved by increasing production of a unit area and enlarging cultivation area. Second, it was suggested that improving and standardizing work operation to increase yielding ability, rationalization of device investment and decrease power cost with energy conservation. The resultfrom improvement of profit by adding plant disease-resistance simulation experiment and also the analysis of tomato growers’ management income and expense showed that damage loose caused by grey mold disease with high agricultural chemical cost and labor costs caused by chemical spray could be cut down. Totally the improvement in tomato profit of maximum 64,252 million yen could be expected. Regard with tomato, maximum improved profit was 552,767 yen per 10a. For cherry tomato, maximum profit was 430,880 yen in tomato cultivation applying a new variety with grey mold disease resistance. The result suggested that a big improvement for tomato growers in agricultural profits could be possible. Therefore, continue study and research results are still expected in the future. The development of the study will continue by the possibility of adding disease-resistance on plants while exploring the expression of the SISWEET15 gene which respond on specific fungus during grey mold initial inflection. If a suppressor system of objected genes made by natural or artificial variation could be successful in tomato cultivation, the gene could be transferred by the objected gene parent using DNA marker breeding. According to this method, it is possible to adopt target gene without genetic recombination. In this study, a model of grey mold disease bacteria was applied which showed a universality of adding disease-resistance on various kinds of plant blight. If the disease-resistance breeding is realized, the improvement of profit by adding plant disease-resistance could be practicable by a simulation analysis in chapter 4. It also possible for tomato growers to improve management profit remarkably. Finally, continue agricultural management can be realizable with improvement of cultivation income. Region economic and employment are relied on almost agricultural management which is mainly performed in countryside. The region agriculture problems are aggravated with increase of aging farmers and cultivation abandonment. The experiments using new technology in this study for improving future agricultural management is expected.