Merensky 6 Rootstock Phytophthora Tolerance Breeding

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Solution Overview

Problem

Current avocado varieties lack resistance or tolerance to Phytophthora cinnamomi, leading to significant economic losses and reduced productivity in avocado farms, with existing rootstocks failing to provide adequate protection against root rot and dieback, and none have gained significant interest from growers due to market preference for the 'Hass' variety.

Innovation Solution

Development of the 'Merensky 6' avocado rootstock, which exhibits superior tolerance to Phytophthora cinnamomi through a breeding program that selected seedlings for root health under infested conditions and was grafted with 'Hass' for field evaluation, demonstrating increased fruit bearing capacity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing avocado rootstocks are used, then avocado trees can be grown, but they lack resistance to Phytophthora cinnamomi causing root rot and dieback

Engineering Contradiction:

Improveresistance to Phytophthora cinnamomiVSAvoidroot rot and dieback

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by selecting and breeding rootstocks with altered genetic parameters that confer resistance to Phytophthora cinnamomi. The breeding program identified rootstocks with superior tolerance through controlled exposure to the pathogen and selection of survivors, thereby changing the resistance parameter of the rootstock population.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If new avocado varieties are developed, then they may have improved characteristics, but none have gained significant interest from growers due to market preference for the Hass variety

Engineering Contradiction:

Improvetolerance to Phytophthora root rotVSAvoidmarket acceptance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies segmentation by separating the functional roles of the avocado plant into scion (fruit-bearing variety) and rootstock (disease-resistant foundation). This allows the Hass variety to maintain its market dominance while the rootstock provides disease resistance, resolving the contradiction between variety innovation and market acceptance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses the rootstock as an intermediary between the soil-borne pathogen and the Hass scion. The rootstock acts as a protective barrier that filters out the harmful Phytophthora cinnamomi, allowing the Hass variety to thrive without direct exposure to the pathogen while maintaining its market-preferred characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If avocado trees are exposed to Phytophthora cinnamomi for breeding selection, then resistant rootstocks can be identified, but the process requires extensive time and resources

Engineering Contradiction:

Improveroot health under Phytophthora pressureVSAvoidbreeding evaluation period

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-exposing rootstock candidates to Phytophthora cinnamomi in controlled mistbeds during the breeding process. This preliminary selection in a controlled environment identifies resistant genotypes before field planting, reducing the time and resources needed for later evaluation and accelerating the breeding program.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUSPP32465P2Avocado rootstock named ‘Merensky 6’

Publication Date: 2020.11.17 WESTFALIA FRUIT ESTATE PTY LTD

AI summary

A new and distinct variety of Persea americana tree imparting high bearing capacity and vigor to the scion cultivar when used as a rootstock. Further, this rootstock exhibits a high tolerance to Phytophthora cinnamomi.