Triploid Citrus RBB7-34 Cultivar Seedless Fruit Pigmentation
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Solution Overview
Problem
Current citrus cultivars, such as 'Glen' Navel orange, face challenges in producing fruit with enhanced internal and external pigmentation, higher °Brix and titratable acidity, and seedlessness, especially in humid sub-tropical climates like Florida, where they often exhibit pale color and seediness under high pollination pressure.
Innovation Solution
The development of a triploid citrus cultivar 'RBB7-34', resulting from a cross between 'LB8-9' and a tetraploid 'Hamlin' sweet orange, which exhibits improved fruit color, higher sugar content, and seedlessness, resembling 'Glen' Navel oranges grown in a Mediterranean climate, achieved through embryo rescue and grafting onto 'Carrizo' citrange rootstock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If diploid citrus cultivars like 'Glen' Navel orange are grown in humid sub-tropical climates, then they can be cultivated successfully, but the fruit exhibit pale color and lower sugar content
Solution Approach 1:
The patent applies ploidy level change from diploid to triploid to fundamentally alter the genetic parameters of the citrus cultivar. This parameter change enables the fruit to produce deeper orange color, higher Brix (sugar content), and higher acidity regardless of the humid sub-tropical climate, effectively resolving the contradiction between climate adaptation and fruit quality
2Productivity
If diploid citrus cultivars are grown under high pollination pressure, then they can reproduce, but the fruit contain seeds which reduces marketability
Solution Approach 1:
The patent utilizes triploidy (change in chromosome number parameter) to achieve seedlessness in the fruit while maintaining reproductive capability through vegetative propagation. The triploid condition causes meiotic irregularities that prevent seed formation, yet the plant can still be propagated asexually to maintain the cultivar, thus resolving the contradiction between reproduction and marketability
3Adaptability or versatility
If embryo rescue and culture are performed to recover seedlings from interploid hybridization, then triploid cultivars can be produced, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by performing embryo rescue and culture techniques during the breeding process to recover and nurture the under-developed embryos that result from interploid hybridization. This preliminary intervention prevents embryo abortion and enables the development of triploid seedlings that would otherwise fail to mature, thus resolving the contradiction between ploidy versatility and process complexity
Data Source
AI summary
The present invention relates to a new and distinct cultivar of citrus tree named ‘RBB7-34’. This triploid cultivar arose from a cross of the seed parent ‘LB8-9’ with pollen from a tetraploid selection of ‘Hamlin’ sweet orange that arose from colchicine treated embryogenic callus. ‘RBB7-34’ produces fruit that resemble Navel orange in size, shape and with the presence of a navel on the blossom end of the fruit, but with greatly enhanced internal and external pigmentation compared with ordinary Navel orange cultivars grown in the humid, sub-tropical Florida climate. Fruit of RBB7-34 are seedless even under intensive cross pollination pressure.